Power prism for folded lenses

ABSTRACT

An optical power prism that may be used in folded lens systems that consists of a glass prism and a glass lens attached to a surface of the prism using a thin layer of optical glue or by optical contact. The glass lens does not have a flange and thus the prism can be smaller than prisms used in conventional power prisms with the same lens effective area, thus reducing the Z-height of the power prism when compared to conventional power prisms. An optical glass may be used for the lens that has a higher refractive index than can be provided by optical plastic which allows the lens to be thinner than plastic lenses. The lenses may be formed by molding a glass wafer to form lens shapes on a first surface of the wafer; the molded wafer is then ground from a second surface to singulate the lenses.

PRIORITY INFORMATION

This application is a continuation of U.S. patent application Ser. No.16/551,521, filed Aug. 26, 2019, which claims benefit of priority ofU.S. Provisional Application Ser. No. 62/726,163, filed Aug. 31, 2018,the content of which are incorporated by reference herein in theirentirety.

BACKGROUND Technical Field

This disclosure relates generally to camera systems, and morespecifically to power prisms for folded lens systems.

Description of the Related Art

The advent of small, mobile multipurpose devices such as smartphones andtablet or pad devices has resulted in a need for high-resolution, smallform factor cameras that are lightweight, compact, and capable ofcapturing high resolution, high quality images at low F-numbers forintegration in the devices. However, due to limitations of conventionalcamera technology, conventional small cameras used in such devices tendto capture images at lower resolutions and/or with lower image qualitythan can be achieved with larger, higher quality cameras. Achievinghigher resolution with small package size cameras generally requires useof an image sensor with small pixel size and a good, compact imaginglens system. Advances in technology have achieved reduction of the pixelsize in image sensors. However, as image sensors become more compact andpowerful, demand for compact imaging lens systems with improved imagingquality performance has increased. In addition, there are increasingexpectations for small form factor cameras to be equipped with higherpixel count and/or larger pixel size image sensors (one or both of whichmay require larger image sensors) while still maintaining a moduleheight that is compact enough to fit into portable electronic devices.Thus, a challenge from an optical system design point of view is toprovide an imaging lens system that is capable of capturing highbrightness, high resolution images under the physical constraintsimposed by small form factor cameras.

SUMMARY OF EMBODIMENTS

Embodiments of an optical prism with refractive power for folded lenssystems are described that may, for example, be used in small formfactor cameras in mobile multipurpose devices such as smartphones andtablet or pad devices. A folded lens system may include one or moreprisms and a lens stack including one or more refractive lens elements.A first prism redirects light from a first optical axis to a secondoptical axis to thus provide a “folded” optical axis for the lenssystem. Using a prism to fold the optical axis may, for example, reducethe Z-height of the lens system, and thus may reduce the Z-height of acamera that includes the lens system. In some folded lens systems, asecond prism may be located at the image side of the lens stack to foldthe optical axis on to a third axis.

In some folded lens systems, a prism with refractive power (referred toas a power prism) may be used. For example, in some camera designs, afolded lens system may require a lens on the object side of the firstprism. Instead of using a separate lens on the object side of the prism,a power prism composed of a prism and a lens deposited on or attached tothe object side surface of the prism may be used. An advantage of thepower prism is that the convex object side surface of the lens can bepositioned closer to the surface of the prism than can be done using aseparate lens, thus reducing Z-height of the folded lens system.

Conventionally, power prisms for folded lens systems are formed using areplication process in which a plastic material is deposited on asurface of a prism, formed into a lens shape, and cured using UV light,or alternatively using a process in which a plastic lens is formed usingan injection molding process and attached to a surface of the prism.However, these conventional processes cause a flange to be formed aroundthe plastic lens, which requires the surface of the prism to be largeenough to accommodate the flange. The size of the surface of the prismto which the lens is attached dictates the size of the prism. As thedimensions of the surface of the prism on which the plastic lens withflange is attached increase, the Z-height of the prism, and thus theZ-height of the power prism including the lens, increases.

Embodiments of a power prism are described that may be used in foldedlens systems. The power prism consists of a glass prism and a glass lensattached to a surface of the prism using optical glue or by opticalcontact. The glass lens does not have a flange. Since the glass lensdoes not have a flange, the dimensions of the prism to which the glasslens is attached can be smaller than the dimensions of a prism to whicha plastic lens with flange is attached. Since the dimensions of thesurface of the prism to which the glass lens is attached are decreased,the Z-height of the prism, and thus the Z-height of the power prismincluding the lens, is decreased. Thus, embodiments of the power prismdescribed herein may provide reduced Z-height when compared to powerprisms formed using conventional methods.

Further, eliminating the flange allows the glass lenses to be thinnerthan the plastic lenses formed by conventional methods. In addition, aglass material may be used for the lens of the power prism that has ahigher refractive index than can be provided by the plastic materialused in conventional methods. The higher refractive index allows theglass lenses to be thinner than the plastic lenses formed byconventional methods. Thus, in addition to reducing Z-height of thepower prism by reducing Z-height of the prism, embodiments of the powerprism described herein may also reduce Z-height by reducing thickness ofthe lens.

Embodiments of a method of manufacturing power prisms are described inwhich the glass lenses are formed by a process in which a glass wafer ismolded to form lens shapes on a first surface of the wafer, and themolded wafer is then ground from a second surface to singulate orseparate the glass lenses. The glass lenses thus formed do not haveflanges. The singulated glass lenses are then attached to the surfacesof glass prisms using a thin layer of optical glue or by optical contactto form the power prisms. In embodiments that use optical glue to attachthe lens to the prism, thickness of the glue, and thus spacing betweenthe plano surface of the lens and the surface of the prism may be <10microns. In embodiments that use optical contact to attach the lens tothe prism, spacing between the plano surface of the lens and the surfaceof the prism may be <5 microns.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a camera with a folded lens system, according to someembodiments.

FIG. 2 illustrates a conventional power prism formed by a process thatdeposits a plastic lens on a surface of a prism.

FIG. 3 illustrates a power prism formed by attaching a singulated glasslens to a surface of a prism, according to some embodiments.

FIGS. 4A through 4D compare a power prism as illustrated in FIG. 3 to apower prism as illustrated in FIG. 2, according to some embodiments.

FIGS. 5A through 5G illustrate a method of manufacture for a power prismas illustrated in FIG. 3, according to some embodiments.

FIGS. 6A through 6F illustrate various alternative embodiments of apower prism as illustrated in FIG. 3.

FIGS. 7A through 7D illustrate various embodiments of cameras withfolded lens systems that include at least one power prism.

FIG. 8 is a flowchart of a method for capturing images using embodimentsof a folded lens system that includes a power prism, according to someembodiments.

FIG. 9 is a flowchart of a method for manufacturing a power prism asillustrated in FIG. 3, according to some embodiments.

FIG. 10 illustrates an example computer system.

This specification includes references to “one embodiment” or “anembodiment.” The appearances of the phrases “in one embodiment” or “inan embodiment” do not necessarily refer to the same embodiment.Particular features, structures, or characteristics may be combined inany suitable manner consistent with this disclosure.

“Comprising.” This term is open-ended. As used in the appended claims,this term does not foreclose additional structure or steps. Consider aclaim that recites: “An apparatus comprising one or more processor units. . . ”. Such a claim does not foreclose the apparatus from includingadditional components (e.g., a network interface unit, graphicscircuitry, etc.).

“Configured To.” Various units, circuits, or other components may bedescribed or claimed as “configured to” perform a task or tasks. In suchcontexts, “configured to” is used to connote structure by indicatingthat the units/circuits/components include structure (e.g., circuitry)that performs those task or tasks during operation. As such, theunit/circuit/component can be said to be configured to perform the taskeven when the specified unit/circuit/component is not currentlyoperational (e.g., is not on). The units/circuits/components used withthe “configured to” language include hardware—for example, circuits,memory storing program instructions executable to implement theoperation, etc. Reciting that a unit/circuit/component is “configuredto” perform one or more tasks is expressly intended not to invoke 35U.S.C. § 112(f), for that unit/circuit/component. Additionally,“configured to” can include generic structure (e.g., generic circuitry)that is manipulated by software and/or firmware (e.g., an FPGA or ageneral-purpose processor executing software) to operate in manner thatis capable of performing the task(s) at issue. “Configure to” may alsoinclude adapting a manufacturing process (e.g., a semiconductorfabrication facility) to fabricate devices (e.g., integrated circuits)that are adapted to implement or perform one or more tasks.

“First,” “Second,” etc. As used herein, these terms are used as labelsfor nouns that they precede, and do not imply any type of ordering(e.g., spatial, temporal, logical, etc.). For example, a buffer circuitmay be described herein as performing write operations for “first” and“second” values. The terms “first” and “second” do not necessarily implythat the first value must be written before the second value.

“Based On.” As used herein, this term is used to describe one or morefactors that affect a determination. This term does not forecloseadditional factors that may affect a determination. That is, adetermination may be solely based on those factors or based, at least inpart, on those factors. Consider the phrase “determine A based on B.”While in this case, B is a factor that affects the determination of A,such a phrase does not foreclose the determination of A from also beingbased on C. In other instances, A may be determined based solely on B.

DETAILED DESCRIPTION

Embodiments of an optical prism with refractive power for folded lenssystems are described that may, for example, be used in small formfactor cameras in mobile multipurpose devices such as smartphones andtablet or pad devices. A folded lens system may include one or moreprisms and a lens stack including one or more refractive lens elements.A first prism redirects light from a first optical axis to a secondoptical axis to thus provide a “folded” optical axis for the lenssystem. Using a prism to fold the optical axis may, for example, reducethe Z-height of the lens system, and thus may reduce the Z-height of acamera that includes the lens system. In some embodiments, a secondprism may be located at the image side of the lens stack to fold theoptical axis on to a third axis.

In some folded lens systems, a prism with refractive power (referred toas a power prism) may be used. For example, in some camera designs, afolded lens system may require a lens on the object side of the firstprism. Instead of using a separate lens on the object side of the prism,a power prism composed of a prism and a lens deposited on or attached tothe object side surface of the prism may be used. An advantage of thepower prism is that the convex object side surface of the lens can bepositioned closer to the surface of the prism than can be done using aseparate lens, thus reducing Z-height of the folded lens system.

Conventionally, power prisms for folded lens systems are formed using areplication process in which a plastic material is deposited on asurface of a prism, formed into a lens shape, and cured using UV light,or alternatively using a process in which a plastic lens is formed usingan injection molding process and attached to a surface of the prism.However, these conventional processes cause a flange to be formed aroundthe plastic lens, which requires the surface of the prism to be largeenough to accommodate the flange. The size of the surface of the prismon which the lens is attached dictates the size of the prism. As thedimensions of the surface of the prism on which the plastic lens withflange is attached increase, the Z-height of the prism, and thus theZ-height of the power prism including the lens, increases. A goal insmall form factor cameras is to reduce Z-height of the cameras for usein thin mobile multipurpose devices. A limiting factor on Z-height inconventional folded lens systems is the Z-height of these conventionalpower prisms.

An optical prism with refractive power (referred to herein as a powerprism) is described that may be used in folded lens systems. The powerprism consists of a glass prism and a glass lens attached to a surfaceof the prism. In some embodiments, instead of using a replicationprocess or injection molding process to form a plastic lens for a powerprism, a process is used in which a glass wafer is molded to form lensshapes on a first surface of the wafer, and the molded wafer is thenground from a second surface to singulate or separate the glass lenses.The glass lenses thus formed do not have flanges. The singulated glasslenses are then attached to the surfaces of glass prisms using a thinlayer (<10 microns) of optical glue or by optical contact. Since theglass lenses do not have flanges, the surface of the prisms to which theglass lenses are attached can be smaller than the prisms used inconventional power prisms as described above, and the power prismsformed by attaching the glass lenses to the prisms are smaller than theconventional power prisms described above. Since the dimensions of thesurface of the prism to which the glass lens is attached are decreased,the Z-height of the prism, and thus the Z-height of the power prismincluding the lens, is decreased.

In addition to reducing the size of the prism by eliminating the addedwidth of the flange, eliminating the thickness of the flange allows theglass lenses to be thinner than the plastic lenses formed byconventional methods. In addition, a glass material may be used for thelens that has a higher refractive index than can be provided by theplastic material used to form lenses in conventional methods. The higherrefractive index allows the glass lenses to be thinner than the plasticlenses formed by the conventional methods.

The prism and lens may be composed of optical glass. In someembodiments, the prism and lens may be composed of the same glassmaterial. However, in some embodiments, the prism and lens may becomposed of different glass materials. In some embodiments, the lens maybe composed of a glass material with an Abbe number that is >45 tocorrect for color aberrations. In some embodiments, the prism may becomposed of a glass material with a higher refractive index than theglass material used in the lens. In some embodiments, the lens may becomposed of a glass material with a refractive index that is >1.5. Insome embodiments, the prism may be composed of a glass material with arefractive index that is >1.7 to provide total internal reflection atthe sloped reflective surface of the prism.

While embodiments of a power prism with a glass lens attached to theobject side of a prism are described, in some embodiments a glass lensmay instead or also be attached to the image side of a prism to form apower prism for use in a folded lens system. Further, while embodimentsof a plano-convex glass lens attached to a prism are described,plano-concave or other types of lenses with a planar surface may also beattached to a prism. Note that the planar surface of a lens is attachedto a surface of the prism.

FIG. 1 illustrates a camera that includes a folded lens system with apower prism, according to some embodiments. FIG. 1 illustratescomponents of a camera 100 that includes a folded lens system with twoprisms 120 and 140 with one or more refractive lenses 132 (three lenses132A, 132B, and 132C, in this example) located in a lens barrel 130between prisms 120 and 140. The prisms 120 and 140 provide a “folded”optical axis for the camera 100. A reflective surface 122 of a firstprism 120 redirects light from an object field from a first axis (AX1)to the lenses 132 on a second axis (AX2). The lenses 132 refract thelight to a reflective surface 142 of a second prism 140 that redirectsthe light onto a third axis (AX3) on which an image sensor 160 of thecamera 100 is disposed. The redirected light forms an image at an imageplane at or near the surface of the image sensor 160. The camera 100may, but does not necessarily, include an infrared (IR) filter 150, forexample located between the second prism 140 and the image sensor 160.The camera 100 may also include an aperture stop 112, for examplelocated on the object side of the first prism 120. The number, shapes,materials, and arrangements of the refractive lens elements 132 in thelens barrel 130 may be selected according to the requirements of theparticular camera 100.

As shown in the example camera 100 of FIG. 1, in some folded lenssystems, a prism with refractive power (referred to as a power prism190) may be used. In this example, to form the power prism 190, a lens110 has been deposited on the object side of prism 120 using areplication process in which a plastic material is deposited on asurface of prism 120, formed into a lens shape, and cured using UVlight. Alternatively, to form the power prism 190, a plastic lens 110may be formed using an injection molding process and attached to asurface of the prism 120. However, these processes causes a flange 114to be formed around the plastic lens 110, which requires the surface ofthe prism 120 to be large enough to accommodate the flange 114. The sizeof the surface of the prism 120 on which the lens 110 is attacheddictates the size of the prism 120. As the dimensions of the surface ofthe prism 120 on which the lens 110 is attached increase, the Z-heightof the prism 120, and thus the Z-height of the power prism 190 includingthe lens 110, increases. A goal in small form factor cameras is toreduce Z-height of the cameras for use in thin mobile multipurposedevices. A limiting factor on Z-height in conventional folded lenssystems is the Z-height of these conventional power prisms 190.

FIG. 2 illustrates a conventional power prism 190 formed by areplication process that deposits a plastic lens 110 (referred to as aplastic lens) on a surface of a prism 120, or alternatively using aprocess in which a plastic lens 110 is formed using an injection moldingprocess and attached to a surface of the prism 120. FIG. 2 shows a sideview (A) and a top view (B) of the power prism 190. As can be seen inFIG. 2, the process forms a flange 114 around the effective area 112 ofthe plastic lens 110. The effective area of a lens may be defined by theeffective diameter of the lens. In optics, the effective diameter of alens may be defined as twice the distance from the geometric center ofthe lens to the edge of the lens shape (in this example, a plano-convexlens shape). In an optical system including an aperture and a sensor,the aperture and focal length of the optical system determine the coneangle of a bundle of rays that come to a focus at an image plane at ornear the sensor. The effective area of a lens in the optical system isor contains the region of the lens in which ray bundles limited by theaperture are affected by the lens. The flange 114 extends outwards fromthe edge of the lens 110 shape. In addition, a margin 116 may berequired around the flange 114 to accommodate slight variations in themanufacturing process. The total diameter of the lens 110 is the width118 at the flange 114 (i.e., the effective diameter of the lens 110 plustwice the width of the flange 114). The width 118 of the lens 110 at theflange 114 requires the surface of the prism 120 on which the lens 110is attached to be large enough to accommodate the flange 114 plus themargin 116. The size of the surface of the prism 120 on which the lens110 is attached dictates the size of the prism 120. As the dimensions ofthe surface of the prism 120 on which the plastic lens 110 is attachedincrease, the Z-height of the prism 120, and thus the Z-height of thepower prism 190, increases. As a non-limiting example, prism 120 mayhave a Z-axis height of about 4 mm, and plastic lens 110 may have atotal thickness of about 0.6 mm (including the thickness of the flange114, e.g. 0.1 mm), for a total Z-axis height for power prism 190 of 4.6mm.

FIG. 3 illustrates a power prism 390 formed by attaching a singulatedglass lens 370 to a surface of a prism 380, according to someembodiments. FIG. 3 shows a side view (A) and a top view (B) of thepower prism 390. As can be seen in FIG. 3, glass lens 370 is formed by aprocess that does not form a flange around the effective area 312 of thelens 370. An example method for forming glass lens 370 is illustrated inFIGS. 5A-5D and FIG. 9. The glass lens 370 may be attached to the prism380 using a thin layer (<10 microns) of optical glue or by opticalcontact, as illustrated in FIGS. 5E-5G and FIG. 9. A margin 316 may berequired around the lens 370 to accommodate slight variations in themanufacturing process. Since lens 370 does not have a flange, thediameter of the lens 370 is the width of the effective area 312 of thelens 370 (i.e., the lens effective diameter). By eliminating the flange,the surface of the prism 380 to which the glass lens 370 is attached canbe smaller than the surface of the prism 120 on which a plastic lens 110with the same effective area as glass lens 370 is deposited using aprocess as shown in FIG. 2. The size of the surface of the prism 120 onwhich the lens 110 is deposited dictates the size of the prism 120.Since the dimensions of the surface of the prism 380 to which the glasslens 370 is attached are decreased, the Z-height of the prism 380, andthus the Z-height of the power prism 390, is decreased when compared tothe power prism 190 of FIG. 2.

In addition to reducing the Z-height of the prism 380 by eliminating theadded width of the flange, eliminating the thickness of the flange mayallow the glass lens 370 to be thinner than the plastic lens 110 formedby conventional methods. In addition, a glass material may be used forthe lens 370 that has a higher refractive index than can be provided bythe plastic material used to form lens 110. The higher refractive indexallows the glass lens 370 to be thinner than the plastic lens 110 formedby conventional methods.

The prism 380 and lens 370 may be composed of optical glass. In someembodiments, the prism 380 and lens 370 may be composed of the sameglass material. However, in some embodiments, the prism 380 and lens 370may be composed of different glass materials. In some embodiments, thelens 370 may be composed of a glass material with an Abbe number thatis >45 to correct for color aberrations. In some embodiments, the prism380 may be composed of a glass material with a higher refractive indexthan the glass material used in the lens 370. In some embodiments, thelens 370 may be composed of a glass material with a refractive indexthat is >1.5. In some embodiments, the prism 380 may be composed of aglass material with a refractive index that is >1.7 to provide totalinternal reflection at the sloped reflective surface of the prism.

FIGS. 4A through 4D compare a power prism 390 as illustrated in FIG. 3to a power prism 190 as illustrated in FIG. 2, according to someembodiments.

FIG. 4A shows a side view of power prism 190 and power prism 390. As canbe seen in FIG. 4A, eliminating flange 114 allows a smaller prism 380 tobe used in power prism 390 than the prism 120 used in power prism 190.Further, as can be seen in FIG. 4A, eliminating the thickness of theflange 114 allows the glass lens 370 to be thinner than the plastic lens110 formed by conventional methods. In addition, a glass material may beused for the lens 370 that has a higher refractive index than can beprovided by the plastic material used to form lens 110, which allows theglass lens 370 to be thinner than the plastic lens 110 formed byconventional methods. FIG. 4A shows the reduction in Z-height of powerprism 390 when compared to power prism 190 due to the elimination of theflange 114 width, and also shows the reduction in Z-height of powerprism 390 when compared to power prism 190 due to elimination of thethickness of the flange 114 combined with the higher refractive index ofthe glass material used in glass lens 370.

As a non-limiting example, prism 120 may have a Z-axis height of about 4mm, and plastic lens 110 may have a total thickness of about 0.6 mm(including the thickness of the flange 114), for a total Z-axis heightfor power prism 190 of 4.6 mm. The total width of the flange 114 may beabout 0.45 millimeters (mm) (0.225 mm on each side of the effectivearea), and thickness of the flange 114 may be about 0.1 mm Eliminatingthe width of the flange 114 may allow the Z-axis height of prism 380(and thus the Z-axis height of power prism 390) to be reduced by about0.45 mm. Thus, the Z-axis height of prism 380 may be about 3.55 mmEliminating the thickness of the flange 114 may allow the thickness oflens 370 (and thus the Z-axis height of power prism 390) to be reducedby 0.1 mm. The higher refractive index of the glass material used inglass lens 370 may allow the thickness of lens 370 (and thus the Z-axisheight of power prism 390) to be reduced by an additional 0.03 mm. Totalreduction on the Z-axis is thus about 0.58 mm. Thus, Z-axis height ofpower prism 390 may be approximately 4.0 mm. Note, however, that powerprisms 390 with larger or smaller Z-axis heights (e.g., within a rangeof 3 mm to 7 mm) may be provided.

FIG. 4B shows a side view of power prism 190 and power prism 390. As canbe seen in FIG. 4B, eliminating flange 114 allows a smaller prism 380 tobe used in power prism 390 than the prism 120 used in power prism 190.In addition to reducing Z-height of the prism 390, eliminating theflange 114 also allows the prism 380 to be reduced in the other (X and Yaxes) dimensions.

FIGS. 4C and 4D show a top view of power prism 190 and power prism 390.As can be seen in FIG. 4C, eliminating flange 114 allows the surface ofprism 380 to which glass lens 370 is attached to be smaller than thesurface of prism 120 on which plastic lens 110 is deposited whileproviding the same size effective area 312 in glass lens 370 as theeffective area 112 of plastic lens 110. As can be seen in FIG. 4D,eliminating flange 114 reduces the extended width needed for prism 380.For prism 120, the extended width on one side is equal to the width ofthe flange plus the width of the margin. The total extended width isthus 2*(flange width+margin width). Given a flange width of 0.225 mm anda margin width of 0.05 mm, the total extended width for prism 120is >0.5 mm. For prism 380, the total extended width is 2*margin width.Given a margin width of 0.05 mm, the total extended with for prism 380is 0.1 mm, or more generally <0.2 mm Eliminating the flange 114 alsoallows the prism 380 to be reduced in X, Y and Z dimensions. Since thedimensions of prism 380 to which the glass lens 370 is attached aredecreased, the Z-height of the power prism 390 is decreased whencompared to the power prism 190.

FIGS. 5A through 5G illustrate a method of manufacture for a power prismas illustrated in FIG. 3, according to some embodiments. In this method,the glass lenses are formed by a process in which a glass wafer ismolded to form lens shapes on a first surface of the wafer, and themolded wafer is then ground from a second surface to singulate orseparate the glass lenses. The glass lenses thus formed do not haveflanges. The singulated glass lenses are then attached to the surfacesof glass prisms using a thin layer of optical glue or by optical contactto form the power prisms. In embodiments that use optical glue to attachthe lens to the prism, thickness of the glue, and thus spacing betweenthe plano surface of the lens and the surface of the prism may be <10microns. In embodiments that use optical contact to attach the lens tothe prism, spacing between the plano surface of the lens and the surfaceof the prism may be <5 microns.

In FIG. 5A, an optical glass wafer 510A is positioned between a top mold500A and a bottom mold 500B. In FIG. 5B, the wafer 510A is pressedbetween molds 500A and 500B to form a molded glass wafer 510B that hasthe desired lens shapes on a first surface of the wafer 510B as shown inFIG. 5C. In FIG. 5D, the molded wafer 510B is positioned in a precisiongrinding and polishing mechanism 520 where it is ground and polishedfrom a second surface to singulate or separate convex-plano glass lenses570 as shown in FIG. 5E. In FIG. 5F, the singulated convex-plano glasslenses 570 are attached to a surface of glass prisms 580 using a thinlayer (<10 microns) of optical glue or by optical contact to form powerprisms 590 as shown in FIG. 5G. In some embodiments, an anti-reflectivecoating may be applied to at least one surface of the glass lenses priorto singulation by grinding, or alternatively after singulation.

The prisms 580 and lenses 570 may be composed of optical glass. In someembodiments, the prisms 580 and lenses 570 may be composed of the sameglass material. However, in some embodiments, the prisms 580 and lenses570 may be composed of different glass materials. In some embodiments,the lenses 570 may be composed of a glass material with an Abbe numberthat is >45 to correct for color aberrations. In some embodiments, theprisms 580 may be composed of a glass material with a higher refractiveindex than the glass material used in the lens. In some embodiments, thelenses 570 may be composed of a glass material with a refractive indexthat is >1.5. In some embodiments, the prisms 580 may be composed of aglass material with a refractive index that is >1.7 to provide totalinternal reflection at the sloped reflective surface of the prism.

FIGS. 6A through 6F illustrate various alternative embodiments of apower prism as illustrated in FIG. 3. While embodiments of a power prismwith a glass lens attached to the object side of a prism are generallydescribed, in some embodiments a glass lens may instead or also beattached to the image side of a prism to form a power prism for use in afolded lens system. Further, while embodiments of a plano-convex glasslens with positive refractive power attached to a prism are described,plano-concave or other types of lenses may also be attached to a prism.

FIG. 6A shows a power prism 690A that consists of a plano-convex glasslens with positive refractive power attached to the object side of aprism. As shown in FIG. 6A, in some embodiments, the aperture stop maybe located at the outer edge of the lens. FIG. 6B shows a power prism690B that consists of a plano-convex glass lens with positive refractivepower attached to the image side of a prism. FIG. 6C shows a power prism690C that consists of a concave glass lens with negative refractivepower attached to the object side of a prism. FIG. 6D shows a powerprism 690D that consists of a concave glass lens with negativerefractive power attached to the image side of a prism. FIG. 6E shows apower prism 690E that consists of a plano-convex glass lens withpositive refractive power attached to the object side of a prism and aplano-convex glass lens with positive refractive power attached to theimage side of the prism. FIG. 6F shows a power prism 690F that consistsof a plano-convex glass lens with positive refractive power attached tothe object side of a prism and a concave glass lens with negativerefractive power attached to the image side of the prism.

FIGS. 7A through 7D illustrate various embodiments of cameras withfolded lens systems that include at least one power prism as illustratedin FIGS. 6A through 6F. FIG. 7A shows a camera 700A that includes, froman object side to an image side, a power prism 790, a lens barrel 730containing one or more refractive lens elements, a standard prism 740,and an image sensor 760. FIG. 7B shows a camera 700B that includes, froman object side to an image side, a power prism 790, a lens barrel 730containing one or more refractive lens elements, and an image sensor760. FIG. 7C shows a camera 700C that includes, from an object side toan image side, a standard prism 740, a lens barrel 730 containing one ormore refractive lens elements, a power prism 790, and an image sensor760. FIG. 7D shows a camera 700D that includes, from an object side toan image side, a first power prism 790A, a lens barrel 730 containingone or more refractive lens elements, a second power prism 790B, and animage sensor 760.

FIG. 8 is a flowchart of an example method for capturing images usingembodiments of a folded lens system that includes a power prism asillustrated in FIGS. 3 through 7, according to some embodiments. Asindicated at 2000, light from an object field is received on a firstaxis, through an aperture stop, at the object side surface of a powerprism. In some embodiments, the power prism may include a glass lens(e.g., a plano-convex lens with positive refractive power) attached tothe object side of a prism. As shown in FIG. 6A, in some embodiments, anaperture stop may be located at the outer edge of the glass lens. Asindicated at 2010, the light received at the object side of the powerprism is redirected by the prism through an image side of the prism to alens stack including one or more refractive lens elements on a secondaxis. In some embodiments, the power prism may include a glass lens(e.g., a concave lens with negative refractive power) attached to theimage side of a prism. As indicated at 2020, the light received from thepower prism is then refracted by the one or more lens elements in thelens stack to a second prism. In some embodiments, the second prism mayalso be a power prism that includes a glass lens attached to at leastone surface of the prism. As indicated at 2030, the second prismredirects the light to form an image at an image plane at or near thesurface of an image sensor or sensor module on a third axis. An imagemay then be captured by the image sensor or sensor module.

In some embodiments, there may be no second prism, for example asillustrated in FIG. 7B. In these embodiments, the lens stack refractslight to form an image at or near the surface of an image sensor orsensor module on the second axis.

In some embodiments, the light may pass through an infrared filter thatmay for example be located between the lens stack and the image sensor.

FIG. 9 is a flowchart of a method for manufacturing a power prism asillustrated in FIG. 3, according to some embodiments. As indicated at2100, an optical glass wafer is molded to form a plurality of lensshapes on a first surface of the wafer, for example as illustrated inFIGS. 5A through 5C. As indicated at 2110, the molded glass wafer isground and polished from a second surface to produce singulated glasslenses with no flanges, for example as illustrated in FIGS. 5D and 5E.As indicated at 2120, the singulated lenses are attached to surfaces ofglass prisms using optical glue or optical contact to produce powerprisms, for example as illustrated in FIGS. 5F and 5G.

Example Computing Device

FIG. 10 illustrates an example computing device, referred to as computersystem 2000, that may include or host embodiments of a camera with afolded lens system that includes at least one power prism as illustratedin FIGS. 3 through 9. In addition, computer system 2000 may implementmethods for controlling operations of the camera and/or for performingimage processing of images captured with the camera. In differentembodiments, computer system 2000 may be any of various types ofdevices, including, but not limited to, a personal computer system,desktop computer, laptop, notebook, tablet or pad device, slate, ornetbook computer, mainframe computer system, handheld computer,workstation, network computer, a camera, a set top box, a mobile device,a wireless phone, a smartphone, a consumer device, video game console,handheld video game device, application server, storage device, atelevision, a video recording device, a peripheral device such as aswitch, modem, router, or in general any type of computing or electronicdevice.

In the illustrated embodiment, computer system 2000 includes one or moreprocessors 2010 coupled to a system memory 2020 via an input/output(I/O) interface 2030. Computer system 2000 further includes a networkinterface 2040 coupled to I/O interface 2030, and one or moreinput/output devices 2050, such as cursor control device 2060, keyboard2070, and display(s) 2080. Computer system 2000 may also include one ormore cameras 2090, for example at least one camera that includes afolded lens system with a power prism as described above with respect toFIGS. 3 through 9.

In various embodiments, computer system 2000 may be a uniprocessorsystem including one processor 2010, or a multiprocessor systemincluding several processors 2010 (e.g., two, four, eight, or anothersuitable number). Processors 2010 may be any suitable processor capableof executing instructions. For example, in various embodimentsprocessors 2010 may be general-purpose or embedded processorsimplementing any of a variety of instruction set architectures (ISAs),such as the x86, PowerPC, SPARC, or MIPS ISAs, or any other suitableISA. In multiprocessor systems, each of processors 2010 may commonly,but not necessarily, implement the same ISA.

System memory 2020 may be configured to store program instructions 2022and/or data 2032 accessible by processor 2010. In various embodiments,system memory 2020 may be implemented using any suitable memorytechnology, such as static random access memory (SRAM), synchronousdynamic RAM (SDRAM), nonvolatile/Flash-type memory, or any other type ofmemory. In the illustrated embodiment, program instructions 2022 may beconfigured to implement various interfaces, methods and/or data forcontrolling operations of camera 2090 and for capturing and processingimages with integrated camera 2090 or other methods or data, for exampleinterfaces and methods for capturing, displaying, processing, andstoring images captured with camera 2090. In some embodiments, programinstructions and/or data may be received, sent or stored upon differenttypes of computer-accessible media or on similar media separate fromsystem memory 2020 or computer system 2000.

In one embodiment, I/O interface 2030 may be configured to coordinateI/O traffic between processor 2010, system memory 2020, and anyperipheral devices in the device, including network interface 2040 orother peripheral interfaces, such as input/output devices 2050. In someembodiments, I/O interface 2030 may perform any necessary protocol,timing or other data transformations to convert data signals from onecomponent (e.g., system memory 2020) into a format suitable for use byanother component (e.g., processor 2010). In some embodiments, I/Ointerface 2030 may include support for devices attached through varioustypes of peripheral buses, such as a variant of the Peripheral ComponentInterconnect (PCI) bus standard or the Universal Serial Bus (USB)standard, for example. In some embodiments, the function of I/Ointerface 2030 may be split into two or more separate components, suchas a north bridge and a south bridge, for example. Also, in someembodiments some or all of the functionality of I/O interface 2030, suchas an interface to system memory 2020, may be incorporated directly intoprocessor 2010.

Network interface 2040 may be configured to allow data to be exchangedbetween computer system 2000 and other devices attached to a network2085 (e.g., carrier or agent devices) or between nodes of computersystem 2000. Network 2085 may in various embodiments include one or morenetworks including but not limited to Local Area Networks (LANs) (e.g.,an Ethernet or corporate network), Wide Area Networks (WANs) (e.g., theInternet), wireless data networks, some other electronic data network,or some combination thereof. In various embodiments, network interface2040 may support communication via wired or wireless general datanetworks, such as any suitable type of Ethernet network, for example;via telecommunications/telephony networks such as analog voice networksor digital fiber communications networks; via storage area networks suchas Fibre Channel SANs, or via any other suitable type of network and/orprotocol.

Input/output devices 2050 may, in some embodiments, include one or moredisplay terminals, keyboards, keypads, touchpads, scanning devices,voice or optical recognition devices, or any other devices suitable forentering or accessing data by computer system 2000. Multipleinput/output devices 2050 may be present in computer system 2000 or maybe distributed on various nodes of computer system 2000. In someembodiments, similar input/output devices may be separate from computersystem 2000 and may interact with one or more nodes of computer system2000 through a wired or wireless connection, such as over networkinterface 2040.

As shown in FIG. 10, memory 2020 may include program instructions 2022,which may be processor-executable to implement any element or action tosupport integrated camera 2090, including but not limited to imageprocessing software and interface software for controlling camera 2090.In some embodiments, images captured by camera 2090 may be stored tomemory 2020. In addition, metadata for images captured by camera 2090may be stored to memory 2020.

Those skilled in the art will appreciate that computer system 2000 ismerely illustrative and is not intended to limit the scope ofembodiments. In particular, the computer system and devices may includeany combination of hardware or software that can perform the indicatedfunctions, including computers, network devices, Internet appliances,PDAs, wireless phones, pagers, video or still cameras, etc. Computersystem 2000 may also be connected to other devices that are notillustrated, or instead may operate as a stand-alone system. Inaddition, the functionality provided by the illustrated components mayin some embodiments be combined in fewer components or distributed inadditional components. Similarly, in some embodiments, the functionalityof some of the illustrated components may not be provided and/or otheradditional functionality may be available.

Those skilled in the art will also appreciate that, while various itemsare illustrated as being stored in memory or on storage while beingused, these items or portions of them may be transferred between memoryand other storage devices for purposes of memory management and dataintegrity. Alternatively, in other embodiments some or all of thesoftware components may execute in memory on another device andcommunicate with the illustrated computer system 2000 via inter-computercommunication. Some or all of the system components or data structuresmay also be stored (e.g., as instructions or structured data) on acomputer-accessible medium or a portable article to be read by anappropriate drive, various examples of which are described above. Insome embodiments, instructions stored on a computer-accessible mediumseparate from computer system 2000 may be transmitted to computer system2000 via transmission media or signals such as electrical,electromagnetic, or digital signals, conveyed via a communication mediumsuch as a network and/or a wireless link. Various embodiments mayfurther include receiving, sending or storing instructions and/or dataimplemented in accordance with the foregoing description upon acomputer-accessible medium. Generally speaking, a computer-accessiblemedium may include a non-transitory, computer-readable storage medium ormemory medium such as magnetic or optical media, e.g., disk orDVD/CD-ROM, volatile or non-volatile media such as RAM (e.g. SDRAM, DDR,RDRAM, SRAM, etc.), ROM, etc. In some embodiments, a computer-accessiblemedium may include transmission media or signals such as electrical,electromagnetic, or digital signals, conveyed via a communication mediumsuch as network and/or a wireless link.

The methods described herein may be implemented in software, hardware,or a combination thereof, in different embodiments. In addition, theorder of the blocks of the methods may be changed, and various elementsmay be added, reordered, combined, omitted, modified, etc. Variousmodifications and changes may be made as would be obvious to a personskilled in the art having the benefit of this disclosure. The variousembodiments described herein are meant to be illustrative and notlimiting. Many variations, modifications, additions, and improvementsare possible. Accordingly, plural instances may be provided forcomponents described herein as a single instance. Boundaries betweenvarious components, operations and data stores are somewhat arbitrary,and particular operations are illustrated in the context of specificillustrative configurations. Other allocations of functionality areenvisioned and may fall within the scope of claims that follow. Finally,structures and functionality presented as discrete components in theexample configurations may be implemented as a combined structure orcomponent. These and other variations, modifications, additions, andimprovements may fall within the scope of embodiments as defined in theclaims that follow.

1.-20. (canceled)
 21. An optical power prism system, comprising: one ormore prisms that each comprise a respective object-side surface, arespective reflective surface, and a respective image-side surface; anda first glass lens attached to the respective object-side surface of oneof the one or more prisms, wherein width of an effective area of thefirst glass lens is the same as diameter of the first glass lens; and asecond glass lens attached to an image-side surface of one of the one ormore prisms, wherein width of an effective area of the second glass lensis the same as diameter of the second glass lens.
 22. The optical powerprism system as recited in claim 21, wherein at least one of the firstglass lens or the second glass lens is composed of a glass material withan Abbe number that is >45.
 23. The optical power prism system asrecited in claim 21, wherein at least one of the one or more prisms iscomposed of an optical glass material with a higher refractive indexthan a glass material used in at least one of the first glass lens orthe second glass lens attached to the at least one of the one or moreprisms.
 24. The optical power prism system as recited in claim 21,wherein at least one of the first glass lens or the second glass lens iscomposed of an optical glass material with a refractive index thatis >1.5.
 25. The optical power prism system as recited in claim 21,wherein at least one of the one or more prisms is composed of an opticalglass material with a refractive index that is >1.7 to provide totalinternal reflection at the reflective surface of the prism.
 26. Theoptical power prism system as recited in claim 21, wherein Z-axis heightof the power prism system is within a range of 3 millimeters to 7millimeters.
 27. The optical power prism system as recited in claim 21,wherein in at least one of the first glass lens or the second glass lensis attached to a surface of one of the one or more prisms using anoptical glue or by optical contact.
 28. The optical power prism systemas recited in claim 21, wherein at least one of the first glass lens orthe second glass lens is a plano-convex lens.
 29. The optical powerprism system as recited in claim 21, wherein at least one of the firstglass lens or the second glass lens is a plano-concave lens.
 30. Theoptical power prism system as recited in claim 21, wherein the firstglass lens is a plano-convex lens, and wherein an aperture stop islocated at an outer edge of the first glass lens.
 31. A lens system,comprising: a plurality of elements arranged along a folded optical axisof the lens system, wherein the plurality of elements comprises: a powerprism system that redirects light received from an object field from afirst portion of the folded optical axis to a second portion of thefolded optical axis, wherein the power prism system includes: one ormore prisms, each prism comprising a respective object side surface, arespective reflective surface, and a respective image-side surface; afirst lens attached to the respective object-side surface of one of theone or more prisms, wherein width of an effective area of the first lensis the same as diameter of the first glass lens; and a second lensattached to an image-side surface of one of the one or more prisms,wherein width of an effective area of the second lens is the same asdiameter of the second lens; and a lens stack comprising one or morerefractive lens elements that refract light output from one of the oneor more prisms along the second portion of the folded optical axis. 32.The lens system as recited in claim 31, wherein one of the one or moreprisms is located on the image side of the lens stack and redirectslight received from the lens stack from the second portion of the foldedoptical axis to a third portion of the folded optical axis.
 33. The lenssystem as recited in claim 31, wherein the first lens is a plano-convexlens.
 34. The lens system as recited in claim 31, wherein the first lensis a plano-concave lens.
 35. The lens system as recited in claim 31,wherein Z-axis height of the power prism system is within a range of 3millimeters to 7 millimeters.
 36. The lens system as recited in claim31, wherein at least one of the one or more prisms is composed of amaterial with a refractive index that is >1.7 to provide total internalreflection at the reflective surface of the prism.
 37. The lens systemas recited in claim 31, wherein the first lens is composed of a materialwith a refractive index that is >1.5.
 38. A camera, comprising: an imagesensor configured to capture light projected onto a surface of the imagesensor; a plurality of elements arranged along a folded optical axis ofthe lens system, wherein the plurality of elements comprises: a powerprism system that redirects light received from an object field from afirst portion of the folded optical axis to a second portion of thefolded optical axis, wherein the power prism system includes: one ormore prisms, each prism comprising a respective object side surface, arespective reflective surface, and a respective image-side surface; afirst lens attached to the respective object-side surface of one of theone or more prisms, wherein width of an effective area of the first lensis the same as diameter of the first glass lens; and a second lensattached to an image-side surface of another one of the one or moreprisms, wherein width of an effective area of the second lens is thesame as diameter of the second lens; and one or more refractive lenselements that refract light output from the one of the one or moreprisms along the second portion of the folded optical axis.
 39. Thecamera as recited in claim 38, wherein the another one of the one ormore prisms is located between the one or more refractive lens elementsand the image sensor and redirects light received from the one or morerefractive lens elements from the second portion of the folded opticalaxis to a third portion of the folded optical axis.
 40. The camera asrecited in claim 38, wherein Z-axis height of the power prism system iswithin a range of 3 millimeters to 7 millimeters.